By comparing relatively close clusters with those more distant, the physical evolution of these gargantuan structures can be traced over time. Mario Livio, an astrophysicist at the Space Telescope Science Institute in Baltimore, says that it does not overturn dogma, but "it is nevertheless an observation that had to be made." Because so many of the early results came from the supernova approach, Livio says, it is important to verify the phenomenon with "a completely independent method."īy studying far-flung galaxy clusters, astronomers are able to look back in time at the state of those objects millions or even billions of years ago, when the light just now reaching us was emitted.
Whereas the existence of dark energy has been well supported for a decade, this new study helps to confirm its presence and to place constraints on just how strong its effects can be.
The researchers said in a teleconference this week that the new look at dark energy is akin to sports referees making calls based on multiple vantage points. Vikhlinin called the findings, which are set to be published in The Astrophysical Journal, "an unambiguous signature of dark energy." Such an effect is not entirely surprising: Astrophysicist Christopher Conselice of the University of Nottingham in England raised this as a likely role for dark energy in a 2007 Scientific American article. Researchers, led by Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics (CfA), found that dark energy seems to restrain the growth of clusters over time, hindering the gravitational clumping of matter that would allow them to grow even more massive. The culprit was labeled dark energy-a hypothesized presence that pervades space and pushes the pieces of the universe apart.Ī new study that examines the growth of galaxy clusters rather than the movement of stars independently confirms the presence of dark energy. Both groups had been studying exploding stars, or supernovae, and used the objects' movement to show that the universe is speeding up. In 1998 two teams of researchers made a milestone cosmological announcement: The universe, long known to be expanding, was not slowing down in its expansion as expected but was in fact accelerating.
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